Heat responsive switches



Sept. 19, 1961 E. F. SWANSON HEAT RESPONSIVE SWITCHES Filed May 5, 1960 j?? INVENTOR.

Ear/76152* j.' wa/m500 BKZ/(wg v ,4 TTORNE United States Patent Y 3,001,052 1 HEAT RESPONSIVE SWITCHES Earnest F. Swanson, R.R. 1, Bristol, Ind. Filed May 5, 1960, Ser. No. 27,103

8 Claims. (Cl. 200--133) This invention relates to improvement in heat responsive switches. The principal objects of this invention are: First, to provide a heat responsiveswitch which will be simple and inexpensive to manufacture and assemble yet accurate and long lived in operation due to the protected position of its contacts.

Second, to provide-a switch of the type described employing a heat expansible actuating element' in which the calibration of the switch can be accomplished with -a minimum of elort during 4assembly of the switch parts under various temperature conditions. y Y

Third, to provide a switch of the type described which utilizes a minimum number of simple'standardized parts which function as connecting terminals and also as openableand closable contacts in the switch assembly in some instances. f

Fourth, to provide a type of switch structure which is readily adaptable to make and break a variety of circuits under different conditions of temperature variation.

Other objects and advantages of the invention will be apparent from a consideration of the following description and claims. The drawings, of which there is one sheet, illustrate one 'highly practical "form of ithef'switch Vand one modified form thereof. e

FIG. l is a fragmentary side elevational view of the switch in one possible application thereof Lto sense the presence Vof a llame in an oilburner;

FIG. l2. is a cross sectional view taken of the line 2-2 in FIG. 1.

FIG. 3 is a cross sectional view taken alongthe plane of the angled line 3-3 in FIG. 2.

FIG. 44 is a fragmentary cross sectional View taken along the plane of the line 4-4in FIG. 3.

FIG. 5 is a fragmentary cross sectional view similar to FIG. 3 but showing a modified arrangement of the switchl parts.

The switchof theinvention as lillustrated is particularly adapted for use ras a safety and regulating switch for oil burners but it has utility in other applications where a heat responsive switch is needed. FIGA shows the nozzle 1 :and supply pipe 2 of an oil burner. or spark points 3 `are shown supported over the nozzle by a bracket 4 as is common. The switch of the invention enclosed in a metal case 5 is shown clamped to the pipe 2 bya bracket or clamp ring 6. Three electricalv conductors or wires 7 extend from the switch to control the operation of the burner 1 and spark points 3 in a variety of dilerent man-ners known'to the art in'response to temperature conditions in Ithecase 5 as created by the burner 1.

Within the case 5 is a circular base Y 8 of heat resistant, electrically insulating material. AThe case 5 is sealed to the base S by a crimped rib 9 and flange 10 so lthe'switch elements are protected from soot, dust and other foreign matter. Extending through the base 8 is a central terminal pin v11 and two terminal and Vcontact pins l2 and 11.3 spaced radially fromthe center pin and along theV plane Starting terminals y -angfularly yfrom each other. `llt is a feature of the invention that the pins 11, 12 and 13 can be identical parts except that the inner ends of the pins 12 `and 13 are desir-ably given a non-corrosive coating such as silver plate as at 14. The pins have outer ends 15 that are bored as at 16 to receive the ends of the wires 7 and be electrically connected thereto as by soldering. A llange 17 is embedded into the base and pins may be press fitted or molded into the base in the desired Vand designed positions to be described.

Pressed around the base of the center pin 11 and embedded into the inner yface of the circular base 8 is an angled metal connector 18 having an upstanding` flange l19. The connector 18is thus electrically connected to the center pin 11 and coacts with a rotatable contact element 20. The contacting element 20 is a metal strip bent -arcuately around the base of an insulating hub 21 rotatably mounted on the irme-r end of the central pin 11 (see FIG. 4). Thecontacting element 20 has radially projecting angularly spaced contact arms 22 and 23 which are desirably silver plated as at 24 where they contact the pins 12 and 13. A flexible electrical connector such as the coil 25 connects the contacting element 20 with the upst'anding llange 19 ofthe connector bracket.

The upper end of the insulating hub 21 has parallel flatted sides 26 which are engaged by the sides of a U- shaped bend in the end of a spirally coiled driving spring 27. The outer end of Ithe spring 27 is lixedly anchored at 28 tothe upstandng arm of a bracket 29 secured to the base disk 8 at 30. The driving spring 27 is of the typewhich will expand and contract upon iluctuation in temperature and is desirably of bimetal construction. No attempt is made to illustrate bimetal as this is a Wellknown expedient. The coiled driving spring 27 is located above the level of the pins 12 and 13 and is electrically insulated therefrom.

In operation of the switch the terminal pins 11, 12 and 13 are connected to the parts to be controlled. 'Ihe central contacting element 20 and its arms 22` and 23 are electrically connected to the center pin 11 through -tlhe'coil spring 25. Depending upon the temperature condition of the spiral driving spring 27 the contacting element 20 may be rotatably adjusted on the insulating hub 21 to position the contact arms 22 and 23 in the desired angular position relative to the pins 12 and 13. The case 5 can be then sealed to the base disk 8 and the switch assembly will thereafter function to make or break contacts between the pin 12 and contact arm 22 or the pin. 13 and the contact arm 23 depending upon the expansion or contraction of the spiral driving spring 27. It is pointed out that any excess lexing of the driving spring 27 beyond that required to make the electrical contacts either in an expanding or contracting relation is readily accommodated by flexing of the contact arms 22 and 23. The silver plated surfaces 114 and 24 of the contacting elements prevent corrosion and sticking of the contacting surfaces so the switch will operate for long periods without attention. No diicult problems are encountered in the assembly and calibration of the switch assembly because as noted, the U-shaped end of the contacting element 20 has merely to be adjusted on 'the hub 21 to the desired angular position relative to the pins 12 `and 13 corresponding to the temperature of the driving spring 27 at disk SAin which a fourth pin 13A is mounted in radially and angularly spaced relation tothe pins 12 and 13 which are the same as in the first form of the switch. The same central mounting pin 11 is lprovided but the insulating hub 21A is arranged to receive a modified Y 'form of contacting element 20A having in addition to the angularly spaced arms 22 and 23 a third vertically and v angularly spaced contacting arm 23A positioned to swing over the upper end of the pin 13 and into contact with the added terminal pin 13A. The pins 13 and 13A can be selectively positioned tomake contact -with their respective contact arms 23 and 23A in either the same or diiierent rotated positions of the insulating hub 21. It will thus be seen that a variety of circuits can be made and broken in response to temperaturevariations by the switch assembly of the invention. rI he combination of elements in the vswitch believed to be patentably novel is set out in the following claims. i l. Inga thermostatic switch assembly, a circular insulating 'base having a central terminal pin projecting therethrough and additional terminal pins prOiecting through said .base in radially andV angularly spaced relation to said central pin, an insulating hub rotatablyrmounted on the inner end of said central pin, a contacting element having a U-shaped bend adjustably and embracingly engaging said hub and having angularly spaced flexible conf tact arms projecting from the hub between said other terminal pins, means electrically connecting said contacting element with said central pin and permitting rotation of said hub, non-corrosive silver coatings on said contact arms and the coacting portions of said other pins, a spiral thermically responsive driving spring having one' end iixedly anchored relative to said base and having its otherV end-drivingly engaged with said hub and positionedbeyond the ends of said terminal pins, anda case enclosing said spring and hub Vand sealed to lsaid base around the inner endsrof said terminal pins.

v2. In-a thermostatic switch assembly, an insulating base `V `having a central terminal pin projecting therethrough and said central pin, a contacting element having a U-shaped bend embracingly engaging said hub and having angularly spaced liexible conta/ct arms projecting from the hub between said other terminal pins, means electrically connecting said contacting element with said central pin and permitting rotation of said hub, non-corrosive coatings on said contact arms and the coacting portions of said other pins, a spiral therrnically responsive driving spring having one end iixedly anchored relative to said base and having its other end drivingly engaged with said huband positioned beyond the ends of said terminal pins, and a case enclosing said spring and hub and sealed to said base around the inner ends of said terminal pins.

3. In a thermostatic switch assembly, an insulating base having a iirst terminal pin projecting therethrough and additional terminal pins projecting through said base in radially and angularly spaced relation to said first pin, an insulating hub rotatably mounted on they inner end of said firstv pin, a contacting element havinga 'U-shaped bendjembracingly engaging said hub and having angularly spaced contacting arms projecting from the hub adjacent Vsaid other terminal pins, means electrically connecting said contacting element with said first pin and permitting rotation of `said hub., non-corrosive coatings on -said contact arms and the coaet-ing-portions of said other pins, a spiral thermicallyresponsive driving spring having one end ixedly anchored relative to said base and having its other end drivingly engaged with said hub and positioned beyond the ends of said terminal pins, and a case enclosing said spring and hub and sealed to Said base around the inner ends of said terminal pins. 'f

4. In a thermostatic switch assembly, an insulating base having a first terminal pin projecting therethrough and an additional terminal pin projecting through said base in radiallylspacedl relation to said first pin, an insulating hub rotatably mounted on the inner end of said iirst pin,

. a contacting element havinga U-shaped bend embracing- 1y engaging said hub and having a contacting arm projecting from the hub adjacent said other terminal pin, means electrically connecting said contacting element with said first pin and permitting rotation of said hub, Vnon-corrosiveV coatings on 'said contact arm and the coacting portion of said otherpin, a spiral thermically responsive driving spring having one lend ixedly anchored relative Vto said-base land having its other end drivingly engaged with said hub andfpositioned beyond the ends of said terminal pins, and a case enclosing said spring andhub vand sealed to 'said base around the innerY ends of said terminal pins.

5. In a thermostatic switch assemblyan insulating base having a first terminal pin projecting therethrough and additional terminalk pins projecting through said base in radially and Vangularly spaced `relation to said rst pin,

an insulating hub rotatably mounted on the inner endV of said irst pin, a contacting element having a U-shaped bend adjustably and embracingly engaging said hub and having angularly spacedcontacting arms projecting from the hub in rotatable contactable relation to said other terminal pins, means'electrically connecting said contacting element with said rst pin and permitting rotation of said hub, a spiral thermically responsive drivingspring having a connection lat one end to said hub and having its other end anchored to said base and positioned beyond the ends of said terminal pins, and a case enclosing said spring and hub and sealed yto said base around the inner ends of said terminal pins.

6. -In a thermostatic switch assembly, an insulating base having a rst terminal pin projecting therethrough and additional terminal pins projecting through Vsaid base in radially and angularly spaced relation to said first pin, .an insulating hub rotatably mounted on the inner end of said first pin, a contacting element having a first connection to said hub and having Vangularly spaced contacting arms j projecting omVV the hub lin rotatable contactable relation to said other terminal pins, means electrically connecting said contacting elementlwith said Itirst pin and permitting rotation of said hub, a spiral thermically responsive driving spring having a second connection at one end to said hub and having its other end anchored to said base and positioned beyond the ends of said terminal pins, one of said connections being angularly adjustable and la case enclosing said spring and hub and. sealed to said base around the inner ends of said terminal pins.

7. A thermostatic switch comprising an insulating base,

.a plurality of terminal pins of like shape projecting through said base in spaced relation and adapted at their o-uter ends for connection to external electrical conductors, an insulating hub rotatably mounted on one of said pins on the inner end thereof, a contacting element having a driven supporting connectionto` said hub and having a1 exible contact arm swingable therewith into contacting engagement with the side of another of said pins, a ther- 8. A thermcstatic switch comprising an insulating base,

s a plurali-ty of terminal pins of like shape projecting through said base in spaced relation `and adapted at their outer ends for connection to extern-a1 electrical conductors, an insulating hub rotatably mounted on one of said pins on the inner end thereof, a contacting element having a driven supporting connection to said hub and having a contact swingable therewith into contacting engagement with 'another of said pins, a thermally responsive spiral driving spring anchored at one end relative to said base and having a rotary driving connection at its other end to Vsaid hub, one of said connections being langul-arly adjust- 6 able, means electrically connecting said contacting element to said one pin, and a case enclosing said spring and the inner ends of said pins and sealed to said base.

' References Cited in the le of this patent UNITED STATES PATENTS 1,955,324 Crichton Apr. 17, 1934 2,348,206 Cunningham et al May 9, 1944 2,377,831 Von Repper-t June 5, 1945 2,579,926 Johnson Dec. 25, 1951 

